Both of our serious presidential candidates present themselves as mavericks willing to tell the truth to the American people. Here are four truths neither will ever let slip to voters:

1. We can’t do much about inequality. The Democrats have focused on the growing inequality of income for some time now. All of my life, actually, and I’m not a young man.

As always, it’s said that government can decrease such inequality by bringing down the top earners, raising up low earners, or both. Socking it to the rich animates some voters, but high marginal taxes have real economic costs and few benefits.

Rising inequality seems tied to increased monetary returns to education. The income difference between have a college degree and a high school degree has grown over the past few decades. So the tax-the-rich road to lesser inequality runs through punishing people who got an education and worked hard.

How about raising up the low earners? We could spend more on education, but the poor would need the skills to take up such opportunities. New studies reviewed by James Heckman, a University of Chicago economist, indicate both cognitive and non-cognitive abilities of children depend heavily on the first five years of life.

Do parents stimulate the child cognitively and teach them how to act right toward others? If not, government can do little to make up for early parental incompetence.

For Heckman, and many others, this research suggests government should get into the business of producing competent parents. The federal government has generally produced meager gains at enormous costs in training people for jobs. There are few reasons to believe the government will do any better training parents.

2. There will be more Iraqs. Senator McCain admires Teddy Roosevelt and sings about bombing Iran but both candidates see crusading abroad as evidence of virtue at home.

Senator Obama might appear dovish, but he seems unlikely to counsel caution if another Rwanda seems possible somewhere south of the Sahara or in Asia. On the left, a humanitarian intervention in the Sudan by the Obama administration would be received totally differently than George W. Bush’s invasion of Iraq.

3. The next administration will increase foreign aid and the price of gas. Both candidates want to “do something” about global warming. Raising the price of gas significantly might make a difference.

Still there would be problems. Developing nations like India and China will not agree to cut their economic growth to reduce carbon emissions. President Obama or President McCain will thus have to pay both nations (and maybe some others) to take part in a global agreement to reduce carbon output. Foreign aid will have to increase by a lot if either candidate actually tries to “do something” about global warming.

4. Entitlements are a normal mess. The benefits promised to current and future Americans under entitlement programs have created huge unfunded liabilities. One day those debts will have to funded by raising taxes, by cutting spending, or by doing both.

That day will come when the world can no longer go on as it is. The entitlement house of cards will come down or be very close to collapse. But that day of reckoning need not happen in the next four years. Hence, the candidates say little about the entitlements mess beyond Obama promising to raise taxes on a small percentage of the electorate.

Both Obama and McCain imply that their brave willingness to tell the truth about politics proves they have enough character to be president. But neither candidate will say anything like the truths outlined here or others that might be mentioned. We might think their reticence suggests character defects and perhaps that is true.

In any event, neither candidate in a close election wants to tell voters things they don’t want to hear. Voters might, after all, cast a ballot for the other guy if you told them unpleasant truths.

So forward we go, safe in the illusion that we need only elect a truth teller unwilling to tell the truths we might most need to hear.